You would have to decompile the model, and rename it, because it would interfere with the original skin.
and some compiling/decompiling stuff.
No it wouldn't. That would be like copying a vmt/vtf pair and renaming it without changing the references inside the actual .vmt text.
That sign already has multiple skins, so if there's one of them that you don't intend to use in your map, then you don't need to decompile anything.
Just find the location of the vmt for the unused skin, and pakrat your own version into your map, in the exact same folder and the exact same name that the original has in the gcf file.